We define disturbance in stream ecosystems to be: any relatively discrete event time that is characterized by a frequency, intensity, and severity outside predictable range, disrupts ecosystem, community, or population structure changes resources the physical environment. Of three major hypotheses relating lotic community structure, dynamic equilibrium hypothesis appears be generally applicable, although specific studies support intermediate model. Differences frequency between lentic...

The importance of terrestrial-aquatic linkages was evaluated by a large-scale, 3-year exclusion terrestrial leaf litter inputs to forest stream. Exclusion had strong bottom-up effect that propagated through detritivores predators. Most invertebrate taxa in the predominant habitat declined either abundance, biomass, or both, compared with nearby reference However, fauna moss habitats changed little, indicating different food webs exist geomorphology. Thus, ecosystem-level consequences...

Estimation of invertebrate biomass is a critical step in addressing many ecological questions aquatic environments. Length-dry mass regressions are the most widely used approach for estimating benthic because they faster and more precise than other methods. A compilation analysis length-mass using power model, M (mass) = L (length)^b, presented from 30 y data collected by authors, primarily southeastern USA, along with published rest North America. total 442 new presented, mostly...

This review focuses on some of the roles macroinvertebrate functional groups, i.e. grazers, shredders, gatherers, filterers, and predators, in stream-ecosystem processes. Many stream-dwelling insects exploit physical characteristics streams to obtain their foods. As consumers at intermediate trophic levels, macroinvertebrates are influenced by both bottom-up top-down forces serve as conduits which these effects propagated. Macroinvertebrates can have an important influence nutrient cycles,...

Abstract: The diversity of life in headwater streams (intermittent, first and second order) contributes to the biodiversity a river system its riparian network. Small differ widely physical, chemical, biotic attributes, thus providing habitats for range unique species. Headwater species include permanent residents as well migrants that travel headwaters at particular seasons or stages. Movement by links with downstream terrestrial ecosystems, do exports such emerging drifting insects. We...

We examined the importance of terrestrial detrital inputs to secondary productivity a headwater stream. Following year pretreatment studies on two streams, we excluded litter (=treatment) one stream while using other as reference. for 3 yr followed by 1 small woody debris (≤10 cm diameter) removal and exclusion. Monthly benthic samples were collected from dominant mixed substrate (cobble, pebble, sand-silt) well moss-covered bedrock outcrop substrates. used randomized intervention analysis...

SUMMARY 1. The effects of catchment urbanisation on water quality were examined for 30 streams (stratified into 15, 50 and 100 km 2 ± 25% catchments) in the Etowah River basin, Georgia, U.S.A. We relationships between land cover (implying use) these catchments (e.g. urban, forest agriculture) macroinvertebrate assemblage attributes using several previously published indices to summarise response. Based a priori predictions as mechanisms biotic impairment under changing cover, additional...

With a growing world population and increasingly demanding consumers, the production of sufficient protein from livestock, poultry, fish represents serious challenge for future. Approximately 1,900 insect species are eaten worldwide, mainly in ...Read More

Life histories and annual production were determined for six species of net—spinning caddisflies in a headwater stream the Tallulah River north Georgia, USA. Five family Hydropsychidae univoltine, whereas sixth, member Philopotamidae, had at least two generations per year. Combined production, as by Hynes method, was 1.0 g/m 2 (ash—free dry mass). Seventy—five percent concentrated largest species, Arctopsyche irrorata Parapsyche cardis. The remaining from highest to lowest percent,...

Nutrient pollution of freshwater ecosystems results in predictable increases carbon (C) sequestration by algae. Tests nutrient enrichment on the fates terrestrial organic C, which supports riverine food webs and is a source CO2, are lacking. Using whole-stream nitrogen (N) phosphorus (P) additions spanning equivalent 27 years, we found that average C residence time was reduced ~50% as compared to reference conditions result pollution. Annual inputs were rapidly depleted via release detrital...

Abstract Stoichiometric relationships between consumers and resources in detritus‐based ecosystems have received little attention, despite the importance of detritus most food webs. We analysed carbon (C), nitrogen (N), phosphorus (P) content invertebrate consumers, basal two forested headwater streams (one reference other nutrient‐enriched). found large elemental imbalances compared with living plant‐based systems, particularly regard to P content, which were reduced enrichment. Enrichment...

We investigated the ability of North Carolina Biotic Index (NCBI) and Ephemeroptera + Plecoptera Trichoptera (EPT) index to track an experimental manipulation invertebrate community resultant alteration several ecosystem‐level processes in a headwater stream at Coweeta Hydrologic Laboratory western Carolina. Indices were calculated from quantitative monthly or bimonthly benthic samples moss‐covered rockface mixed substrate habitats, as well habitat‐weighted values based on proportion each...

Food webs based on flows of organic matter were developed for two small streams to examine food web response a large reduction in detrital inputs. At the study site, Coweeta Hydrologic Laboratory southern Appalachians, leaf litter inputs and associated microbial assemblages are main energy source headwater streams. We eliminated one stream using net placed over first 180 m from its origin. flow reference litter-excluded months, July December year 1 exclusion, effects exclusion trophic base...

SUMMARY. 1. The insecticide methoxychlor was applied seasonally to one of three small headwater streams in the southern Appalachian Mountains North Carolina, U.S.A. initial application caused massive invertebrate drift (>1,000,000 organisms/week) and resulted a community with few shredders reduced abundances most insect taxa. 2. Bacterial densities microbial respiration rates were not affected by treatment. 3. Disruption significant reductions leaf litter processing (50–74% reduction...

Although the effects of nutrient enrichment on consumer–resource dynamics are relatively well studied in ecosystems based living plants, little is known about manner which influences and productivity consumers resources detritus-based ecosystems. Because nutrients can stimulate loss carbon at base detrital food webs, higher may be fundamentally different than what expected for living-plant-based webs typically increase basal carbon. We experimentally enriched a headwater stream two years to...

To assess the importance of woody debris in two relatively unaltered Coastal Plain streams southeastern United States, a line intersect technique, developed by foresters, was used to estimate volume, mass, surface area, and spatial distribution. The ash-free dry mass in-channei material 6.5 kg/m 2 stream channel bottom sixth-order Ogeechee River 5.0 fourth-order Black Creek. Most wood is located near erosional bank these meandering streams. These estimates are much higher than expected for...

By comparing distributions of functional group production among different habitats in an Appalachian mountain stream, the influence site-specific geomorphology upon overall composition animal community was demonstrated. replicated monthly sampling, substrate particle size distributions, current velocity, standing crops benthic organic matter, and macrofauna were measured each three principal habitats: bedrock-outcrop, riffle, pool. Samples taken at randomly assigned locations relative number...

Three pairs of cobble riffle study sites were established in a second-order stream North Carolina and logs added to the downstream at each site. At log addition transects, depth increased, current velocity decreased, substratum was covered by sand silt, both coarse fine particulate organic matter increased dramatically. Log additions had less dramatic effects on uptake lengths ammonium, nitrate, phosphate, but they immediate significant impacts invertebrate community structure: abundances...

1. Changes in benthic invertebrate community structure following 16 years of forest succession after logging were examined by estimating abundance, biomass and secondary production streams draining a forested reference recovering clear‐cut catchment. Benthic abundance was three times higher, two higher the disturbed stream. 2. Comparison 1, 5 clear‐cutting indicated that proportion scrapers had decreased, whereas shredders increased. Functional group percentage similarity stream more similar...

1. The flow of energy through food webs with similar species can vary both space and time. river continuum concept (RCC) provides a useful framework for predicting variability in the biota availability along streams. We estimated organic matter (g m −2 year −1 ) webs, arrayed stream, that had different resource inputs. Four sites were sampled Little Tennessee River, North Carolina, U.S.A.: two fifth order sites, one sixth seventh site. dominant is leaf detritus upstream reach (the site),...